Fire Resistance Classes and Test Methods | Fireproof Safes & Vaults

In addition to burglary, fire is one of the greatest risks when storing valuable assets. To ensure a reliable and comparable level of protection, fireproof safes and cabinets are tested according to internationally recognised standards.

Lighter standards: NT Fire 017 and EN 15659 (LFS)

NT Fire 017

Developed in Scandinavia, this is one of the most common fire resistance standards worldwide. The safe is exposed in a furnace at approx. 927 °C for 60, 90 or 120 minutes. Certifications exist for both paper and data media:

NT Fire 017 Paper: max. internal temperature 150 °C, protection for paper (60, 90 or 120 minutes).
NT Fire 017 Data: max. internal temperature 50 °C, protection for digital media (60, 90 or 120 minutes).
NT Fire 017 Diskette: max. internal temperature 30 °C, protection for highly sensitive magnetic media (60, 90 or 120 minutes).

EN 15659 (LFS – Light Fire Storage)

A European standard developed by ECB·S as a lighter classification alongside EN 1047-1. The safe is tested at approx. 850 °C for 30 or 60 minutes, applicable only for paper:

LFS 30P: max. internal temperature 150 °C, protection for paper for 30 minutes.
LFS 60P: max. internal temperature 150 °C, protection for paper for 60 minutes.

Limitations of lighter standards

For both NT Fire 017 and EN 15659, the safe is removed from the furnace immediately after the test period and artificially cooled. There is no natural cooling phase included. In a real fire, however, a safe continues to heat up for hours, which may cause the contents to be lost even if the safe has passed one of these lighter tests.

Stricter standards: EN 1047-1 and UL 72

The standards EN 1047-1 and UL 72 are among the strictest and most reliable fire resistance tests, as they simulate not only the fire itself but also the aftermath, including natural cooling and potential building collapse.µ

EN 1047-1

Developed in Germany, this standard is considered the most demanding in Europe. The test consists of two parts:

Fire test: 60 or 120 minutes at approx. 1090 °C.
Impact and fire test: the safe is first heated for 30 minutes at 850 °C, then dropped from a height of 9.15 m onto rubble to simulate a building collapse, and finally placed back in the furnace for 30 minutes at 1000 °C, followed by natural cooling.

Classifications:

S60P / S120P: paper protection, max. internal temperature 150 °C (absolute limit 177 °C).
S60D / S120D: protection for digital media, max. 50 °C.
S60DIS / S120DIS: protection for highly sensitive data media, max. 30 °C.

UL 72

The American standard UL 72 is comparable to EN 1047-1, but applies its own classifications. The safe is exposed to approx. 1000 °C for 30, 60, 120 or 240 minutes.

Class 350: protection for paper (max. 177 °C).
Class 150: protection for microfilm.
Class 125: protection for digital media (max. 55 °C).

A drop test may be included, but it is optional. As with EN 1047-1, a natural cooling phase is part of the procedure.

Importance of natural cooling

In a real fire, a safe does not cool down immediately after extinguishing but continues to heat up internally for hours. Only EN 1047-1 and UL 72 explicitly include this natural cooling phase in their protocols. As a result, they provide the highest level of protection, both during the fire itself and in the critical hours that follow.

Standards That Provide No Guarantee

Certain standards such as DIN 4102 and BS 476 relate only to the fire reaction of construction materials and were not designed for safes or security cabinets. DIN 4102 essentially means that the material itself is non- or low-combustible, but it says nothing about the protection of the contents in the event of a fire.

References such as “according to DIN 4102” should never be mistaken for a true fire resistance test: such a safe does not protect the contents against fire. If you are offered a fireproof cabinet certified only to DIN 4102, do not hesitate to request a test report.

For reliable protection, one should only rely on safes and fireproof cabinets tested according to recognised standards such as NT Fire 017, EN 15659, EN 1047-1 and UL 72.

Overview of fire-resistance classes

Fire-resistance classes for paper

Standard / class	Exposure time	External temperature	Max. internal temperature	Drop test	Cooling phase
EN 15659 – LFS 30P	30 min	approx. 850 °C	≤ 170 °C	No	No
EN 15659 – LFS 60P	60 min	approx. 850 °C	≤ 170 °C	No	No
NT Fire 017 – 60P	60 min	approx. 927 °C	≤ 170 °C	No	No
NT Fire 017 – 90P	90 min	approx. 927 °C	≤ 170 °C	No	No
NT Fire 017 – 120P	120 min	approx. 927 °C	≤ 170 °C	No	No
EN 1047-1 – S 60P	60 min	approx. 1,090 °C	≤ 170 °C	Yes (mandatory)	Yes
EN 1047-1 – S 120P	120 min	approx. 1,090 °C	≤ 170 °C	Yes (mandatory)	Yes
UL 72 – Class 350	60–120 min	approx. 1,000 °C	≤ 177 °C	Optional	Yes

Fire-resistance classes for digital media

Standard / class	Exposure time	External temperature	Max. internal temperature	Drop test	Cooling phase
NT Fire 017 – 60D	60 min	approx. 927 °C	≤ 55 °C	No	No
NT Fire 017 – 90D	90 min	approx. 927 °C	≤ 55 °C	No	No
NT Fire 017 – 120D	120 min	approx. 927 °C	≤ 55 °C	No	No
EN 1047-1 – S 60D	60 min	approx. 1,090 °C	≤ 55 °C	Yes (mandatory)	Yes
EN 1047-1 – S 120D	120 min	approx. 1,090 °C	≤ 55 °C	Yes (mandatory)	Yes
UL 72 – Class 150	60–120 min	approx. 1,000 °C	≤ 66 °C	Optional	Yes
UL 72 – Class 125	60–120 min	approx. 1,000 °C	≤ 52 °C	Optional	Yes

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